This invention relates to roofing material, and in particular to roofing shingles, having a novel backing which renders the material pliable and imparts improved characteristics such as resistance to damage from hail.
Roofing material has an upper surface intended to be exposed to weather and a lower surface facing in the direction opposite to the upper surface. Traditionally, the lower surface or back of roofing material such as shingles has been covered with finely ground mineral material (fines) so that the asphalt backing does not adhere to contiguous roofing material when packaged for transport and storage. Such finely divided materials include mica flakes, copper slag, coal slag, sand, talc and silica dust.
In many regions the roofing materials on buildings, particularly the shingles on residential dwellings, are damaged by hail. The damage is caused by the impact of the hail stones on shingles resulting in cracking, tearing, snapping or imperceptible damage to the shingles"" structure which can render the shingles less resistant to the elements of wind, rain, snow and ice. Frequently, such damage requires the costly replacement of roofing materials to prevent the elements from entering into the building. Accordingly, it is an object of the invention to provide more energy absorbing roofing materials, particular shingles, which better absorb the impact of hail and are therefore less susceptible to damage during hail storms.
In accordance with the invention, roofing materials such as shingles are improved by adhering to at least a part of their back surface or lower surface a backing material which may be made of polyester fibers, woodpulp, glass fibers, cotton fibers, wool fibers, carpet material, nylon fibers, rayon fibers, acrylic fibers, polyolefin fibers, polypropylene fibers and recycled plastics fibers, binder material, crosslinking agents and mixtures thereof. In a preferred embodiment, the backing material is a mat consisting essentially of a mixture of glass fiber, polyester fiber and a latex binder.
Asphalt roofing materials, including shingles, are manufactured by following conventional procedures. Bituminous prepared roofing has heretofore been extensively manufactured using as a base a fibrous web such as a sheet of roofing felt or fiberglass mat, impregnating the fibrous web with a bituminous material and coating one or both surfaces of the impregnated web with a weather-resistant bituminous coating material. The bituminous coating material usually contains a mineral filler such as slate flour or powdered limestone. Sometimes one or more fibrous sheets are laminated with one or more bituminous layers. Usually there is applied to the bituminous coating on the surface intended to be exposed to the weather a suitable granular material such as slate granules or mineral surfacing. Finely divided materials such as mica flakes, talc, silica dust or the like may be made adherent to the non-weather exposed surface of the roofing shingle to prevent sticking of the adjacent layers of the roofing material in packages.
In the present invention, the fines on the back of roofing material are replaced with a backing material or mat that renders the product more energy absorbent than it otherwise would be. In a preferred embodiment, the mat includes a non-woven layer of wet laid polyester staple fibers. However, a woven polyester mat may also be employed. Polyester mats are resistant to punctures and tears and thus, their inclusion on the backs of roofing materials renders the materials less susceptible to damage from hail.
The backing material is adhered to the face of the back of the shingle in lieu of fines, granules or other standard backing material at the slating drum stage of conventional shingle manufacturing. The inventive shingles are manufactured using a standard line where asphalt coats the moving web and mineral granules are dropped on the upper surface of the hot asphalt coated web. In accordance with the invention, a roll of mat enters from the back side of the line at 90xc2x0. The roll runs through an unwind stand, a splicer, an accumulator, and directional changing rolls to feed the mat under the slating drum. Alternatively, the mat may enter from the top and be fed directly to the back of the slating drum, in essence replacing the back surfacing equipment normally utilized. The application technique is similar to the current industry technique of applying release tape to the back of the shingle at the slating drum.
Polyester melts at approximately 350xc2x0 . and the asphalt which coats the moving web in shingle manufacturing is typically about 400xc2x0 F. Thus, the polyester fuses to the back of the shingle. However, because cooling occurs rapidly, the back side of the polyester mat facing away from the shingle remains intact.
Shingles made with the inventive polyester backing have better tear strength than standard shingles backed with finely divided granules. The inventive shingles are less susceptible to machine breaks and fractures and tears during field application, i.e. they tolerate installation abuse. Further, the inventive shingles pass impact tests despite their light product weight. Moreover, they demonstrate increased nail holding ability and maintain structural integrity at elevated temperatures. Also, the mat fused to the back of the shingle is less likely to crack than the asphalt coating. Thus an enhanced impact resistant seal against water penetration is provided. Additionally, the mat adheres readily to the sealant (usually a compounded bituminous material such as those disclosed in U.S. Pat. No. 4,559,267) superposed on at least some portion of the roofing material to prevent blow offs.
The inventive backing may be applied to any design or formulation of roofing material such as built up roofing materials, roll roofing and modified roll products, but it is particularly effective as shingle backing. As heretofore noted, a variety of materials may be employed in providing the backing of the inventive roofing materials. Such backing material, which may provide partial or full coverage of the lower surface of the shingles, enables the shingles to demonstrate enhanced physical properties even though the internal composition of the shingle remains unchanged. Regarding handlability, the exposed portion of the inventive shingle feels more substantial compared to the conventional product. The inventive roofing material is pliable at cold temperatures but not limp at hot temperatures.